The Japan Coast Guard on Monday released a condensed 30-minute video of its failed attempt to prevent activists from Hong Kong from making an unauthorized landing on the Senkaku Islands on Aug. 15.

“We decided to release the video to show that the coast guard took appropriate measures against the protesters,” said Takahiro Okushima, director of the Japan Coast Guard’s Territorial Waters Guard, Security Division.

The video was edited down from about seven hours of footage that began at 11:52 a.m., when the patrol boats started transmitting footage to coast guard headquarters, and ended at 6:50 p.m., when they took control of the Hong Kong fishing boat after the cat-and-mouse chase.

Footage that could reveal Japan’s patrolling techniques, formations and distances from the Chinese boat were edited out of the video, the guard said.

The video showed a coast guard cutter firing water cannons at the activists’ vessel and pushing against it to force the boat away from Uotsuri, the largest of the Senkaku islets.

It also showed Chinese activists hurling bricks and concrete blocks at two of the patrol boats, which some critics said would justify the pressing of criminal charges for obstruction of official duties.

Yet, the coast guard official said counterattacks are not sufficient evidence for prosecution because the tactics did not hamper the coast guard from taking measures to stop the ship and did not inflict major damage to the patrol boats.

The release of the video came amid rising criticism of the government, which arrested the 14 Hong Kong-based activists but repatriated them quickly without pressing charges to avoid escalating the territorial spat with China.

Members of opposition-leading Liberal Democratic Party were pressing the government to release the video to provide evidence for prosecuting the activists.

Even after Hong Kong-based Phoenix TV aired video footage taken by its reporters, who accompanied the protesters, the government was on the fence about disclosing the coast guard’s footage because it might help other protesters make similar landings.

The Japan Coast Guard has a record of releasing accident footage except in a few cases. In 2010, when a Chinese fishing boat collided with Japan Coast Guard cutters, the Japanese government kept the footage from the public and showed it only to select Diet members. The video was later uploaded to YouTube by a coast guard navigator who was disgruntled by the government’s reluctance to air the video.